"In proof of stake protocols, however, validators can come and go, and even the absolute size of the validator set can shrink and grow greatly over time. 80% of the validator set at one time may well be smaller than 20% of the validator set at another time, and what in a fixed-set model is clearly equivocation, in a dynamic-set model may not involve any equivocation at all. How do we deal with this?"

The explanation of STARKS. “ZK-STARKs resolve one of the primary weaknesses of ZK-SNARKs, its reliance on a ‘trusted setup’. They also come with much simpler cryptographic assumptions, avoiding the need for elliptic curves, pairings and the knowledge-of-exponent assumption and instead relying purely on hashes and information theory; this also means that they are secure even against attackers with quantum computers.”

The white-paper. “We present an authenticated data feed system called Town Crier (TC). TC acts as a bridge between smart contracts and existing web sites, which are already commonly trusted for non-blockchain applications. It combines a blockchain front end with a trusted hardware back end to scrape HTTPSenabled websites and serve source-authenticated data to relying smart contracts.”